PM Messages staying in Outbox forever

[suziclue]

How come the PM messages on this board stay in the Outbox for so long? Been over half an hour. I'm not sure if it's going through. Is this normal?

[LDM]

It's cause the person you have sent the message to, hasn't opened or received it yet where they hadn't logged in.

They stay in your outbox until the person receives it in their inbox.